Mobile wireless communication devices, such as a cellular telephone or a wireless personal digital assistant, can provide a wide variety of communication services including, for example, voice communication, text messaging, internet browsing, and electronic mail. Mobile wireless communication devices can operate in a wireless communication network of overlapping “cells”, each cell providing a geographic area of wireless signal coverage that extends from a base transceiver station (BTS). Whether idle or actively connected, a mobile wireless communication device can be associated with a “serving” cell in a wireless communication network and be aware of neighbor cells to which the mobile wireless communication device can also associate. The quality of a communication link between the mobile wireless communication device and the BTS can vary based on the distance between them and on interference included in received signals at either end of the communication link. As the mobile wireless communication device moves further away from the BTS, eventually a neighbor cell can provide an equal or better performing communication link than the current serving cell. The mobile wireless communication device can include a process for determining if and when to switch cells with which it associates. If the mobile wireless communication device is actively connected to the serving cell, then the process of switching to a neighbor cell is known as “handoff.” For a mobile wireless communication device that is associated with a serving cell in an “idle” state, the process of associating with a neighbor cell is known as “cell reselection.”
When a mobile wireless communication device seeks to associate with a wireless communication network, such as after a power on initialization, the mobile wireless communication device can search for cells located in its vicinity. If a cell is located that has sufficient performance quality to provide a wireless communication link, then the mobile wireless communication device can associate with that cell. The mobile wireless communication device can then be “camped” on a particular “serving” cell in the wireless communication network of cells. While camped on the serving cell, the mobile wireless communication device can listen to messages broadcast from the serving cell BTS as well as from other BTS located in neighbor cells. If the mobile wireless communication device determines that a neighbor cell can provide a higher quality communication link than a current serving cell, then the mobile wireless communication device can disassociate from the current serving cell and associate with the neighbor cell, in a process known as “cell reselection,” typically after waiting for a certain time period. By waiting before performing cell reselection, the mobile wireless communication device can avoid bouncing between different cells as the quality of the communication links between the mobile wireless communication device and several nearby cells changes.
Waiting a fixed period of time before cell reselection, however, can result in a mobile wireless communication device continuing to associate with a serving cell to which the performance of a connection is degrading when the mobile wireless communication device seeks to originate an active connection. An active connection between the “idle” mobile wireless communication device and the BTS in the current serving cell can be initiated by the mobile wireless communication device or by the BTS through an exchange of a series of messages. While camped on a serving cell, a wireless mobile communication device can initiate a connection with the serving cell with which it is associated, but not with a neighbor cell, even if the performance of a connection between the mobile wireless communication device and the neighbor cell can result in a higher quality connection. The performance of a connection between the mobile wireless communication device and the serving cell can degrade sufficiently rapidly that the mobile wireless communication device cannot handoff to a neighbor cell before the connection drops.
Thus there exists a need to evaluate a quality of a link between a serving cell and a mobile wireless communication device and to reselect to a better quality cell if available prior to call origination by the mobile wireless communication device. Monitoring the quality of multiple neighbor cells in addition to the serving cell can improve a success rate of call origination.